Structural elucidation of a compound, whether a synthesis product or an extract from a natural source generally requires a number of analytical techniques. Infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance (NMR) spectroscopy can provide extensive chemical information. NMR can provide structural information and also information on both intermolecular and intramolecular dynamics. Applications of NMR range from determination of three-dimensional structures of large proteins to the analysis of very small amounts of products from combinatorial syntheses. Furthermore, NMR is a nondestructive analytical method.
High resolution NMR probes typically have an ‘inner coil’ for irradiation and detection of a first nuclear species, and a second larger coil, coaxial with the inner coil, for irradiation of one or more other nuclear species. The two coils are oriented 90° with respect to each other to minimize coupling between the two coils. Capacitive coupling has previously been used to form double-tuned high resolution NMR probes for 1H-2H, 13C-15N and 1H-19F.
In U.S. Pat. No. 3,789,832 to Damadian a method for imaging is described in which spatial localization is achieved by means of applying a spatially inhomogeneous static magnetic field where the signal is measured in the small homogeneous region of the static field. In U.S. Pat. No. 4,301,410 to Wind et al., a method is disclosed for spin imaging solids using NMR spectroscopy by rotating the sample about an axis at a particular angle to the NMR static external magnetic field, with a magnetic field gradient with a spatial distribution which is related to the sample spinning axis is synchronously rotated with the sample. In U.S. Pat. No. 4,654,593 to Ackerman, a method for NMR imaging uses a nonmagnetic moving object positioned in the field of a RF excitation coil and a magnetic field where the object is of a low conductivity so as to be substantially transparent to electromagnetic radiation at the NMR frequency and the nonmagnetic object is subjected to periodic motion while transverse magnetization is generated, and a short duration phase-encoding magnetic field gradient pulse is applied in a specified direction to the moving nonmagnetic object, where the magnetic field gradient is turned off and a free induct ion decay signal is detected. In U.S. Pat. No. 5,227,724 to Cory et al., a method for measuring the distribution of the extent of molecular transport along two orthogonal directions, and further for measuring the anisotropy of molecular transport is disclosed. In U.S. Statutory Invention Registration. No. H1218 to Cory et al., a method of NMR imaging where spatial coupling of the sample with a receiver device is varied using pulsed magnetic field gradients and the sample is moved relative to the receiver device, or the spatial coupling of the receiver device and the sample is electronically altered, is disclosed. Kuhns, P. L. et al. describe the use of inductive coupling for series linked tuning of resonant circuits, J. Magnetic Resonance, “Inductive Coupling and Tuning in NMR Probes: Applications”, 78 (1988) 69-76. Hoult, D. I. and Tomanek, B. describes the use of mutually inductive coils and investigates field strength, losses and signal to noise, “Use of Mutually Inductive Coupling in probe Design”, Concepts in Magnetic Resonance, 15(4) (2002) 262-285, Wiley Periodicals, Inc.